Endoplasmic reticulum stress-mediated induction of SESTRIN 2 potentiates cell survival

// Svetlana Saveljeva 1,2,* , Patricia Cleary 1,2,* , Katarzyna Mnich 1,2,* , Abiodun Ayo 1,2 , Karolina Pakos-Zebrucka 1,2 , John B. Patterson 3 , Susan E. Logue 1,2,* and Afshin Samali 1,2,* 1 Apoptosis Research Centre, NUI Galway, Ireland 2 School of Natural Sciences, NUI Galway, Ireland 3 MannKind Corporation, Valencia, California, USA * These authors have contributed equally to this work Correspondence to: Afshin Samali, email: // Keywords : SESTRIN 2, ER stress, UPR, cell death, autophagy Received : August 14, 2015 Accepted : January 25, 2016 Published : February 22, 2016 Abstract Upregulation of SESTRIN 2 (SESN2) has been reported in response to diverse cellular stresses. In this study we demonstrate SESTRIN 2 induction following endoplasmic reticulum (ER) stress. ER stress-induced increases in SESTRIN 2 expression were dependent on both PERK and IRE1/XBP1 arms of the unfolded protein response (UPR). SESTRIN 2 induction, post ER stress, was responsible for mTORC1 inactivation and contributed to autophagy induction. Conversely, knockdown of SESTRIN 2 prolonged mTORC1 signaling, repressed autophagy and increased ER stress-induced cell death. Unexpectedly, the increase in ER stress-induced cell death was not linked to autophagy inhibition. Analysis of UPR pathways identified prolonged eIF2α, ATF4 and CHOP signaling in SESTRIN 2 knockdown cells following ER stress. SESTRIN 2 regulation enables UPR derived signals to indirectly control mTORC1 activity shutting down protein translation thus preventing further exacerbation of ER stress.